This invention relates to gear systems for use in transmissions to provide infinitely variable and smooth transmission of speed and other motion transformations.
The problem which is prevalent with transmissions and other motion transformation devices is the difficulty of producing a continuously variable and smooth desired output from an input motion in the desired speed ratio. Most transmission devices do not accomplish the transformation of input motion to desired output motion in a smooth manner, resulting in speed fluctuations evidenced by "jerking" motions and inefficiency resulting in loss of speed and torque between the input and output of the transmission.
Thus, there is a need for a device like the present invention for the transmission of mechanical power which is capable of transforming an available input motion to an output motion with the desired characteristics.
The relevant prior art contains some patents which have attempted to fulfill the above referenced need, but none have done so successfully or in the same manner as the present invention.
For instance, U.S. Pat. No. 3,919,895 by Kerr, issued Nov. 8, 1975, discloses a variable output transmission that uses two sets of four "sawtooth" (or square-wave) gears and a summing device which incorporates beveled gear trains and over-running clutches. Due to the sharp transition in the sawtooth pattern, undesirable dynamics and certain inefficiencies are expected to occur in motion transformation.
U.S. Pat. No. 4,055,091 also by Kerr, issued Oct. 25, 1977, discloses a variable output transmission which is essentially the same as the first Kerr patent except that it has a new control element and gear-running clutches are repositioned, but it is still a variation of the same device.
Another U.S. Pat. No. 4,969,860 by Takami, et al., issued Nov. 13, 1990, discloses a stepless transmission mechanism that uses non-circular gears which generate a sawtooth wave function. The latter device contains a rotating housing for the input and output planetary gear trains which requires special balancing considerations due to phase shift. Furthermore, this device produces a sharp transition in speed ratio and gear profile.
U.S. Pat. No. 4,909,101 by Terry, Sr., issued Mar. 20, 1990, also discloses a continuously variable transmission in which power is input to a sun gear which, in turn, drives four planetary gears surrounding the sun gear in a circular fashion. Although the latter device attempts to accomplish the same goal as the present invention it is very different from a mechanical standpoint.
Another U.S. Pat. No. 4,944,718 by Takahara, et al., issued Jul. 31, 1990, shows an angular velocity modulating device which is also very different from the present invention.
Contrary to the inventions in the prior art which is restricted to constant input/output relations, the present invention employs sets of non-circular gears, either spur or spiral, in conjunction with clutches and other circular gear trains for dividing, multiplying and summing with the necessary phase changes to produce the desired relation between input and output motion. In the present invention the desired motion characteristics can be synthesized by summation of appropriate segments of the output from the non-circular gears activating "on/off" clutches using mechanical, electric or fluid control as well as self activation, based on the relevant movement of engaging elements. The resulting transmission device of the present invention can be utilized in almost any vehicle where motion transformation is desired, such as automobiles and bicycles.